I've had this question come across my desk a number of times: "What is the difference between the various Android storage locations?" Although, at first blush, the answer might be simple (you have phone storage and SD card storage), it's not quite so cut and dry. You should understand the different types of Android storage for a number of reasons. First and foremost — where do you install your apps? Local storage? SD card? And what is that pesky USB storage that keeps filling up?

Let's look beyond the veil and see the finer details about Android storage.

Types

The type of Android storage can be broken down like this:

ROM

RAM

Internal storage

Phone storage

USB storage

The breakdown of the above storage used to be very cut and dry:

Operating system lived on ROM

Apps lived on internal storage

App data lived on USB storage

Files lived on phone storage

As apps grew larger and users wanted more of them, it became necessary to also use SD card storage to house apps. With that in mind, let's take a look at each.

ROM

You'll often hear of Android users flashing a custom ROM onto their devices. You can't (typically) gain access to this storage type, and with good reason, because this is where your operating system resides. The name ROM is a bit misleading. ROM was, for the longest time, an acronym for Read Only Memory. This is not as much the case with the Android ROM. It's better to consider the ROM as a type of firmware (though that's not 100% accurate either). This "firmware" can be replaced by a modified version. There are plenty of sites to download custom ROMs, but replacing a ROM is not for the average user.

RAM

The Android RAM is exactly as you would expect. It's a non-upgradable, Random Access Memory that is permanently attached to your phone's system board. Many Android devices will ship with 1 or 2 GB of RAM. Of this total, your operating system will use a portion of that. So, even if you know your phone has 1 GB of RAM, you'll never have the total amount of RAM available, because the operating system must use some. With this in mind, never buy an Android phone with less than 512 MB of RAM. With this small amount of RAM, the Android OS will not leave you much RAM to run applications, which means apps will run very slowly.

Internal storage

This is the storage that's permanently attached to your phone. You cannot remove or upgrade this storage. Internal storage is particularly important, because this is where your apps are stored. If you buy a budget or entry-level phone, you'll probably find around 512 MB of internal storage. With this low amount of storage, you'll only be able to install a few apps. So, you want to shoot for a minimum of 1 to 2 GB. Many higher-end Android phones have 16 to 32 GB of internal storage — and that's a lot of room for apps.

Now, this is where it gets a bit murky. Some Android phones allow you to install apps to the external storage (SD card). Some phones require a third-party app (from the Google Play Store) to do this. Some phones (such as the Motorola Moto X) do not offer external storage at all, so you have to be careful not to fill up your internal storage.

Phone storage

Ah, we get even more confusing here, right? Not really. Phone storage is actually simple. This type of storage is a portion of the internal storage that houses all of the pre-installed applications that come with the device (apps that are not part of the operating system).

Let's muddy the water up even more. With some devices, you'll find phone storage used for both internal and phone storage. In fact:

USB storage

This is another tricky piece of the puzzle. If you look in a file manager, you might find a location called /sdcard/. Within that location, there may be a folder called usbstorage. That folder is used when the device is connected to a PC in Media Transfer Protocol (MTP) mode, for transferring data between the device and the PC. If you enable MTP mode on your device, when you plug it into your PC, it should show up as a removable drive. That is USB storage.

And that is the long and short of Android storage. Confused yet? Most users won't ever concern themselves with this topic. Power users, on the other hand, might want to know how the different types of storage function on the Android platform.

Have you come across issues with Android storage? If so, what are they? Or have you found the Android storage structure to be ideal? Share your thoughts about Android storage in the discussion thread below.

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About Jack Wallen

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website jackwallen.com.

Full Bio

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website jackwallen.com.